By Ron Cowen
![](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2006/08/6069.jpg?resize=300%2C135&ssl=1)
Pluto aficionados, rejoice! Pluto is a planet. So are the giant asteroid Ceres, Pluto’s moon Charon, and a large outer-solar system object called 2003 UB313. The solar system has 12 planets instead of the familiar 9, according to a proposal that the General Assembly of the International Astronomical Union (IAU) will vote on next week in Prague, Czech Republic.